Environmental evaluation of 3D printed concrete walls considering the life cycle perspective in the context of social housing

Wall construction is the most common application for 3D concrete printing (3DCP). This construction technique requires a printing material with specific rheological characteristics that are usually achieved through high cement consumptions, reaching more than 1000 kg/m³. It is well known that large-scale cement consumption is a worldwide concern, mainly due to carbon dioxide emissions. Thus, in the context of 3DCP structures, this environmental concern becomes even more relevant. Therefore, this work investigated the environmental performance, by means of the Life Cycle Assessment (LCA) methodology, evaluating 14 environmental impact categories of 3DCP walls, and comparing them with conventional construction techniques in a social housing context of a Brazilian case study. The results confirmed that cement consumption provides the greatest contribution to the impact potentials for most of the evaluated categories, reaching 93% for climate change. So, materials that can be used to replace cement, such as supplementary cementitious materials (SCM), are important alternatives. In general, the comparative results showed that 3DCP can have a similar environmental performance to conventional construction techniques, when, instead of evaluating 1 m³ of concrete, the functional unit evaluated is 1 m2 of wall. Sensitivity analysis carried out showed that the printing parameter variations that most affect the consumption of concrete cause the greatest changes in potential environmental impacts, while alterations in the energy consumption, almost do not influence the total values of the potential impacts. Finally, this study presents a roadmap and a pathway for designers, developers, builders and researchers of 3DCP to decrease the life cycle environmental impacts. •Due to the high consumption of cement in 3DCP mixtures, the use of SCM is essential.•Most LCA on 3DCP found in literature evaluated few environmental impact categories.•Environmental comparisons between 3DCP and conventional construction are scarce.•Environmental impacts of 3DCP can be similar to conventional construction techniques.•Guidelines for environmentally viable solutions in 3DCP walls are proposed.